The promoter region of the EGF receptor gene contains SP1 binding sites which probably regulate its expression. A number of other possible regulatory sites have been detected in exonuclease protection assays. A full length cDNA clone of the EGF receptor gene has been constructed and used to make sense and antisense RNA. The sense RNA is translated into EGFR protein. Antisense RNA specifically inhibits this translation. Mutants of KB cells with low levels of EGF receptor have been isolated and are being characterized.